To eliminating the safety loophole of gas concentration out-of-limit during ventilation ceasing for mine main fan switchover, we present a main fan hot standby strategy for mine main fan switchover. For the multi-couplings, great lag, nonlinearity of mine ventilation system, to stabilize the ventilation-rate underground to eliminate safety loophole and particle pollution under mine, one of the four air-doors was controlled with Fuzzy-PID, the other air-doors and the working-condition variation of main fans were treated as disturbance. In practical application, it makes good performance for invariant ventilation in the main fan switchover process.